Quadruped locomotion

This chapter considers locomotion in living machines, focusing particularly on mammals and on the possibility of designing mammal-like quadrupedal robots. Locomotion is the movement of an organism or a machine from one place to the other, covering a defined minimal distance. In organisms, locomotion usually is driven by a central element and/or appendices. Vertebrates are characterized by the existence of a spine and the mechanics of an endoskeletal system. The amphibio-reptile type of vertebrate locomotion shows oscillations of the body stem mainly in the horizontal, which are coupled to the ground by legs with two long segments. The vertical oscillations of the body stem in the mammal type of quadrupedal locomotion are coupled to the ground by legs with three long segments. For any size of animal and any allometric relation between mass and ground reaction force the resonance mechanisms of gravitational and spring-mass-pendula are tuned to one each other. Elongated feet allow torque exchange with the substrate.